Antigen expression determines adenoviral vaccine potency independent of IFN and STING signaling.

Recombinant adenoviral vectors (rAds) are lead vaccine candidates for protection against a variety of pathogens, including Ebola, HIV, tuberculosis, and malaria, due to their ability to potently induce T cell immunity in humans. However, the ability to induce protective cellular immunity varies among rAds. Here, we assessed the mechanisms that control the potency of CD8 T cell responses in murine models following vaccination with human-, chimpanzee-, and simian-derived rAds encoding SIV-Gag antigen (Ag). After rAd vaccination, we quantified Ag expression and performed expression profiling of innate immune response genes in the draining lymph node. Human-derived rAd5 and chimpanzee-derived chAd3 were the most potent rAds and induced high and persistent Ag expression with low innate gene activation, while less potent rAds induced less Ag expression and robustly induced innate immunity genes that were primarily associated with IFN signaling. Abrogation of type I IFN or stimulator of IFN genes (STING) signaling increased Ag expression and accelerated CD8 T cell response kinetics but did not alter memory responses or protection. These findings reveal that the magnitude of rAd-induced memory CD8 T cell immune responses correlates with Ag expression but is independent of IFN and STING and provide criteria for optimizing protective CD8 T cell immunity with rAd vaccines.

A novel, live-attenuated vesicular stomatitis virus vector displaying conformationally intact, functional HIV-1 envelope trimers that elicits potent cellular and humoral responses in mice.

Though vaccination with live-attenuated SIV provides the greatest protection from progressive disease caused by SIV challenge in rhesus macaques, attenuated HIV presents safety concerns as a vaccine; therefore, live viral vectors carrying HIV immunogens must be considered. We have designed a replication-competent vesicular stomatitis virus (VSV) displaying immunogenic HIV-1 Env trimers and attenuating quantities of the native surface glycoprotein (G). The clade B Env immunogen is an Env-VSV G hybrid (EnvG) in which the transmembrane and cytoplasmic tail regions are derived from G. Relocation of the G gene to the 5'terminus of the genome and insertion of EnvG into the natural G position induced a ∼1 log reduction in surface G, significant growth attenuation compared to wild-type, and incorporation of abundant EnvG. Western blot analysis indicated that ∼75% of incorporated EnvG was a mature proteolytically processed form. Flow cytometry showed that surface EnvG bound various conformationally- and trimer-specific antibodies (Abs), and in-vitro growth assays on CD4+CCR5+ cells demonstrated EnvG functionality. Neither intranasal (IN) or intramuscular (IM) administration in mice induced any observable pathology and all regimens tested generated potent Env-specific ELISA titers of 10(4)-10(5), with an IM VSV prime/IN VSV boost regimen eliciting the highest binding and neutralizing Ab titers. Significant quantities of Env-specific CD4+ T cells were also detected, which were augmented as much as 70-fold by priming with IM electroporated plasmids encoding EnvG and IL-12. These data suggest that our novel vector can achieve balanced safety and immunogenicity and should be considered as an HIV vaccine platform.

Coadministration of polyinosinic:polycytidylic acid and immunostimulatory complexes modifies antigen processing in dendritic cell subsets and enhances HIV gag-specific T cell immunity.

Currently approved adjuvants induce protective Ab responses but are more limited for generating cellular immunity. In this study, we assessed the effect of combining two adjuvants with distinct mechanisms of action on their ability to prime T cells: the TLR3 ligand, polyinosinic:polycytidylic acid (poly I:C), and immunostimulatory complexes (ISCOMs). Each adjuvant was administered alone or together with HIV Gag protein (Gag), and the magnitude, quality, and phenotype of Gag-specific T cell responses were assessed. For CD8 T cells, all adjuvants induced a comparable response magnitude, but combining poly I:C with ISCOMs induced a high frequency of CD127(+), IL-2-producing cells with decreased expression of Tbet compared with either adjuvant alone. For CD4 T cells, combining poly I:C and ISCOMs increased the frequency of multifunctional cells, producing IFN-γ, IL-2, and TNF, and the total magnitude of the response compared with either adjuvant alone. CD8 or CD4 T cell responses induced by both adjuvants mediated protection against Gag-expressing Listeria monocytogenes or vaccinia viral infections. Poly I:C and ISCOMs can alter Ag uptake and/or processing, and we therefore used fluorescently labeled HIV Gag and DQ-OVA to assess these mechanisms, respectively, in multiple dendritic cell subsets. Poly I:C promoted uptake and retention of Ag, whereas ISCOMs enhanced Ag degradation. Combining poly I:C and ISCOMs caused substantial death of dendritic cells but persistence of degraded Ag. These data illustrate how combining adjuvants, such as poly I:C and ISCOMs, that modulate Ag processing and have potent innate activity, can enhance the magnitude, quality, and phenotype of T cell immunity.

Rapid, quantitative mapping of anti-HIV type 1 envelope serum antibody specificities.

A new generation of extremely broad and potent neutralizing antibodies (bNAbs) has been isolated from HIV-infected subjects. This has refocused interest in the sites of vulnerability targeted by these bNAbs and in the potential for designing Envelope (Env) immunogens that display these sites. Standard methods for evaluating HIV-1 vaccine candidates do not enable epitope mapping on the HIV Env spike, the target for NAbs. To meet the need for rapid analysis of Ab specificity, we designed a multiplexed, quantitative mapping assay that can test for serum Ab competition for the binding of an HIV-1 Env gp120 to a panel of bNAbs directed to different sites of vulnerability on the Env that do not compete for one another in the assay. Using serum samples from rabbits immunized with various DNA prime/gp120 protein boost vaccines we were able to detect serum Ab competition for multiple classes of bNAbs in the postimmune samples that were significantly higher than background competition detected in samples obtained prior to vaccination. Importantly, application of this novel assay to our ongoing HIV-1 Env viral vector studies in mice has allowed us to distinguish qualitative differences in the Ab elicited by various regimens that ELISA cannot. Furthermore, pooled immunoglobulin from HIV-infected donors (HIVIg) competes for binding to the bNAb panel whereas a control pool from HIV-negative donors does not, highlighting the utility of this assay for human studies. This novel assay will add value in rational immunogen design and in the detailed, qualitative evaluation of binding and, potentially, neutralizing Abs elicited by natural infections and HIV-1 vaccine candidates.

Comparative analysis of the magnitude, quality, phenotype, and protective capacity of simian immunodeficiency virus gag-specific CD8+ T cells following human-, simian-, and chimpanzee-derived recombinant adenoviral vector immunization.

Recombinant adenoviral vectors (rAds) are the most potent recombinant vaccines for eliciting CD8(+) T cell-mediated immunity in humans; however, prior exposure from natural adenoviral infection can decrease such responses. In this study we show low seroreactivity in humans against simian- (sAd11, sAd16) or chimpanzee-derived (chAd3, chAd63) compared with human-derived (rAd5, rAd28, rAd35) vectors across multiple geographic regions. We then compared the magnitude, quality, phenotype, and protective capacity of CD8(+) T cell responses in mice vaccinated with rAds encoding SIV Gag. Using a dose range (1 × 10(7)-10(9) particle units), we defined a hierarchy among rAd vectors based on the magnitude and protective capacity of CD8(+) T cell responses, from most to least, as: rAd5 and chAd3, rAd28 and sAd11, chAd63, sAd16, and rAd35. Selection of rAd vector or dose could modulate the proportion and/or frequency of IFN-γ(+)TNF-α(+)IL-2(+) and KLRG1(+)CD127(-)CD8(+) T cells, but strikingly ∼30-80% of memory CD8(+) T cells coexpressed CD127 and KLRG1. To further optimize CD8(+) T cell responses, we assessed rAds as part of prime-boost regimens. Mice primed with rAds and boosted with NYVAC generated Gag-specific responses that approached ∼60% of total CD8(+) T cells at peak. Alternatively, priming with DNA or rAd28 and boosting with rAd5 or chAd3 induced robust and equivalent CD8(+) T cell responses compared with prime or boost alone. Collectively, these data provide the immunologic basis for using specific rAd vectors alone or as part of prime-boost regimens to induce CD8(+) T cells for rapid effector function or robust long-term memory, respectively.

Type I IFN induced by adenovirus serotypes 28 and 35 has multiple effects on T cell immunogenicity.

Recombinant adenovirus (rAd) vectors are being investigated as vaccine delivery vehicles in preclinical and clinical studies. rAds constructed from different serotypes differ in receptor usage, tropism, and ability to activate cells, aspects of which likely contribute to their different immunogenicity profiles. In this study, we compared the infectivity and cell stimulatory capacity of recombinant adenovirus serotype 5 (rAd5), recombinant adenovirus serotype 28 (rAd28), and recombinant adenovirus serotype 35 (rAd35) in association with their respective immunogenicity profiles. We found that rAd28 and rAd35 infected and led to the in vitro maturation and activation of both human and mouse dendritic cells more efficiently compared with rAd5. In stark contrast to rAd5, rAd28 and rAd35 induced production of IFN-α and stimulated IFN-related intracellular pathways. However, the in vivo immunogenicity of rAd28 and rAd35 was significantly lower than that of rAd5. Deletion of IFN-α signaling during vaccination with rAd28 and rAd35 vectors increased the magnitude of the insert-specific T cell response to levels induced by vaccination with rAd5 vector. The negative impact of IFN-α signaling on the magnitude of the T cell response could be overcome by increasing the vaccine dose, which was also associated with greater polyfunctionality and a more favorable long-term memory phenotype of the CD8 T cell response in the presence of IFN-α signaling. Taken together, our results demonstrate that rAd-induced IFN-α production has multiple effects on T cell immunogenicity, the understanding of which should be considered in the design of rAd vaccine vectors.

Protective T cell immunity in mice following protein-TLR7/8 agonist-conjugate immunization requires aggregation, type I IFN, and multiple DC subsets.

The success of a non-live vaccine requires improved formulation and adjuvant selection to generate robust T cell immunity following immunization. Here, using protein linked to a TLR7/8 agonist (conjugate vaccine), we investigated the functional properties of vaccine formulation, the cytokines, and the DC subsets required to induce protective multifunctional T cell immunity in vivo. The conjugate vaccine required aggregation of the protein to elicit potent Th1 CD4+ and CD8+ T cell responses. Remarkably, the conjugate vaccine, through aggregation of the protein and activation of TLR7 in vivo, led to an influx of migratory DCs to the LN and increased antigen uptake by several resident and migratory DC subsets, with the latter effect strongly influenced by vaccine-induced type I IFN. Ex vivo migratory CD8-DEC205+CD103-CD326- langerin-negative dermal DCs were as potent in cross-presenting antigen to naive CD8+ T cells as CD11c+CD8+ DCs. Moreover, these cells also influenced Th1 CD4+ T cell priming. In summary, we propose a model in which broad-based T cell-mediated responses upon vaccination can be maximized by codelivery of aggregated protein and TLR7/8 agonist, which together promote optimal antigen acquisition and presentation by multiple DC subsets in the context of critical proinflammatory cytokines.

CD8+ T cell responses following replication-defective adenovirus serotype 5 immunization are dependent on CD11c+ dendritic cells but show redundancy in their requirement of TLR and nucleotide-binding oligomerization domain-like receptor signaling.

Replication-defective adenovirus serotype 5 (rAd5) is the most potent recombinant vector for eliciting CD8 T cell responses in humans. In this study, the innate mechanisms that influence T cell responses following rAd5 immunization were assessed in mice. Using rAd5 expressing enhanced GFP (eGFP-rAd5), we show that rAd5 transfects CD11c(+) dendritic cells (DCs) in draining lymph nodes in vivo following s.c. or i.m. immunization. Among distinct DC subsets, eGFP expression was highest in CD11c(+)CD8(-)B220(-) with a lower frequency detected in CD11c(+)CD8(+)B220(-) and CD11c(+)B220(+) plasmacytoid DCs. CD11c(+) DCs but not CD11c(-) cells from mice immunized with rAd5 encoding the SIINFEKL peptide induced proliferation of naive OT-I CD8 T cells. Furthermore, CD11c(+)CD8(+)B220(-) was the most potent DC subset for eliciting naive OT-I CD8 T cell proliferation. Of note, mice with pre-existing immunity to rAd5 had a substantial decrease in eGFP expression in DCs, which was associated with approximately 2-fold decrease in Th1 and complete inhibition of CD8 responses. Thus, pre-existing rAd5 immunity has a greater influence on CD8 compared with CD4 T cell responses. In terms of how innate cytokines and signaling pathways influenced T cell immunity following rAd5 immunization, we show that the magnitude and quality of CD8 T cell responses are partially dependent on MyD88 but independent of IL-12, type I IFN, apoptosis-associated speck-like protein, nucleotide-binding oligomerization domain-like receptor protein 3, and IL-1. Taken together, these data demonstrate a critical role for CD11c(+) DCs for CD8 responses but striking redundancy for innate cytokines and signaling by TLR and nucleotide-binding oligomerization domain-like receptor pathways.

IL-10 production differentially influences the magnitude, quality, and protective capacity of Th1 responses depending on the vaccine platform.

The quality of a Th1 response can be a prospective correlate of vaccine-mediated protection against certain intracellular pathogens. Using two distinct vaccine platforms, we evaluate the influence of interleukin (IL) 10 production on the magnitude, quality, and protective capacity of CD4(+) T cell responses in the mouse model of Leishmania major infection. Multiparameter flow cytometry was used to delineate the CD4(+) T cell production of interferon (IFN) gamma, IL-2, tumor necrosis factor (TNF), and IL-10 (or combinations thereof) after vaccination. Immunization with a high dose of adenovirus (ADV) expressing leishmanial proteins (MML-ADV) elicited a limited proportion of multifunctional IFN-gamma(+)IL-2(+)TNF(+) Th1 cells, a high frequency of IL-10-producing CD4(+) T cells, and did not protect against subsequent challenge. Surprisingly, in the absence of IL-10, there was no change in the magnitude, quality, or protective capacity of the Th1 response elicited by high-dose MML-ADV. In contrast, after immunization with MML protein and CpG (MML + CpG), IL-10 limited the production of IL-12 by DCs in vivo, thereby decreasing the generation of multifunctional Th1 cells. Consequently, three immunizations with MML + CpG were required for full protection. However, inhibiting IL-10 at the time of immunization enhanced the magnitude and quality of the Th1 response sufficiently to mediate protection after only a single immunization. Overall, we delineate distinct mechanisms by which vaccines elicit protective Th1 responses and underscore the importance of multifunctional CD4(+) T cells.

Multifunctional TH1 cells define a correlate of vaccine-mediated protection against Leishmania major.

CD4+ T cells have a crucial role in mediating protection against a variety of pathogens through production of specific cytokines. However, substantial heterogeneity in CD4+ T-cell cytokine responses has limited the ability to define an immune correlate of protection after vaccination. Here, using multiparameter flow cytometry to assess the immune responses after immunization, we show that the degree of protection against Leishmania major infection in mice is predicted by the frequency of CD4+ T cells simultaneously producing interferon-gamma, interleukin-2 and tumor necrosis factor. Notably, multifunctional effector cells generated by all vaccines tested are unique in their capacity to produce high amounts of interferon-gamma. These data show that the quality of a CD4+ T-cell cytokine response can be a crucial determinant in whether a vaccine is protective, and may provide a new and useful prospective immune correlate of protection for vaccines based on T-helper type 1 (TH1) cells.

Hepatic resection with cryotherapy to involved or inadequate resection margin (edge freeze) for metastases from colorectal cancer.

BACKGROUND: In patients undergoing liver resection for colorectal liver metastases, a resection edge either involved by tumour or with the tumour extending to within 1 cm is associated with a high risk of liver recurrence and survival is reduced markedly. METHODS: Twenty-six patients underwent cryotherapy of the resection edge following liver resection for metastases from colorectal carcinoma with an involved or inadequate (less than 1 cm) resection margin. RESULTS: At a median follow-up of 23 (range 1-47) months four patients were alive and disease free, and 21 had developed recurrence, of whom 13 had died. One patient died following surgery. Sixteen patients developed recurrences involving the liver, only five of which were at the resection margin. CONCLUSION: Cryotherapy to involved or inadequate resection margins improves local disease control considerably. The use of resection edge cryotherapy might allow a greater proportion of patients with liver metastases to be usefully treated and help to avoid high-risk resections.

High serum carcinoembryonic antigen concentration in patients with colorectal liver metastases is associated with poor cell-mediated immunity, which is predictive of survival.

BACKGROUND: Carcinoembryonic antigen (CEA) inhibits lymphocyte function and patients with cancer have lower cell-mediated immunity (CMI) than the normal population. To test this association an investigation was made of the relationship between CMI score, CEA level and survival. METHODS: CEA level, CMI score and other variables were compared with the survival time of 109 patients with colorectal liver metastases using Cox regression analysis. RESULTS: There was a significant association between CMI and CEA categories (P = 0.04, chi 2 test). The odds of patients with normal CMI having a CEA level in the upper quartile observed for all patients were 22 per cent of those of patients with depressed CMI (odds ratio 0.22 (95 per cent confidence interval (c.i.) 0.03-0.90), mid-P corrected). The median survival time of patients with normal CMI scores was 943 days compared with 488 days for those with depressed CMI (P = 0.03, log rank test; P = 0.04, Peto). The mortality risk of patients with normal CMI at entry to the study was, in the first 2 years of treatment, 40 per cent of that of patients with depressed CMI (95 per cent c.i. for relative risk 0.20-0.82, Cox regression). CONCLUSION: In patients with colorectal hepatic metastases, CMI is predictive of survival and a raised serum CEA level is associated with depressed CMI.

Major upper gastrointestinal haemorrhage associated with hepatic arterial chemoperfusion.

BACKGROUND: The present study reviews the nature of upper gastrointestinal complications of hepatic arterial chemoperfusion at a tertiary referral centre for the treatment of hepatic malignancy. METHODS: The patients involved in the present study all had major upper gastrointestinal (GI) haemorrhage and were undergoing hepatic arterial chemoperfusion. RESULTS: Eight patients had major upper GI haemorrhage. Three of these patients were not referred for surgical management, and all three patients died. The five patients who were admitted or transferred to our unit and who underwent surgery all survived. CONCLUSIONS: These complications are probably caused by extravasation of 5-fluorouracil (5-FU) following thrombosis of the gastroduodenal artery. The resulting cavity may perforate into the hepatic artery, portal vein, duodenum or biliary tree. Surgeons and oncologists should be aware of these complications. If upper abdominal pain occurs, chemoperfusion should cease immediately and an urgent investigation, which may include catheter angiography, gastroscopy and computed tomography (CT) scanning, should be carried out to exclude an hepatic artery pseudo-aneurysm.

Australian experience of cryoablation of liver tumors: metastases.

The authors' clinical experience of treating almost exclusively inoperable liver malignancy in 149 patients by cryotherapy is reviewed. There was only one 30-day death; morbidity was modest. Postoperative carcinoembryonic antigen (CEA) changes were extremely predictive of outcome in patients with liver metastases from colorectal cancer. For the group in which CEA levels returned to the normal range, median survival exceeded 1000 days. In addition, the authors reported encouraging results with cryotherapy as an adjunct to resection.

Primary resection and synchronous regional hepatic chemotherapy or cryotherapy for colorectal cancer with liver metastases.

Twenty-two patients with colorectal cancer and synchronous unresectable hepatic metastases were treated by resection the primary tumour with concurrent insertion of an Infusaid infusaport system for regional chemoperfusion (hepatic arterial 20, portal venous 2). Four patients in addition had cryotherapy the liver metastases. Morbidity from the synchronous procedures was minimal. Median survival was 10 months. Four patients with poorly-differentiated tumours had a poor response, with a median survival of 3.75 months.

A randomized trial of cimetidine with 5-fluorouracil and folinic acid in metastatic colorectal cancer.

Cimetidine has demonstrated a survival benefit in a randomized trial as adjuvant therapy for gastric cancer. We have demonstrated expression of histamine receptors on colon cancer cell lines and inhibition of their growth with cimetidine. Cimetidine also activates suppressor T cells and stimulates cell-mediated immunity. We therefore performed a randomized controlled clinical trial to determine the effect of cimetidine 400 mg given twice daily in conjunction with chemotherapy vs chemotherapy alone. Thirty-eight patients were randomized and 35 patients were eligible for further analysis. Both groups were well matched for pre-treatment characteristics. There was no difference in overall response. There was, however, a significantly increased rate of CEA response in the cimetidine group. Four of 11 patients (36%) in the cimetidine group had a CEA response compared to none of eight in the control. Meaningful comparisons of overall survival cannot yet be made. This study demonstrates that cimetidine has encouraging activity in increasing CEA response in patients with metastatic colorectal cancer treated with chemotherapy. This observation needs to be extended in a larger randomized study, which is currently underway.

Effect of hepatic artery chemotherapy on survival of patients with hepatic metastases from colorectal carcinoma treated with cryotherapy.

Thirty-eight patients with unresectable multiple liver metastases from colorectal carcinoma were treated with either hepatic artery chemotherapy (HAC) and cryotherapy (n = 27) or cryotherapy alone (n = 11). Follow-up survival data were summarized using Cox regression. Allowing for the effect of the pathology of the primary tumor and the preoperative carcinoembryonic antigen (CEA) level, those patients who did not receive HAC after cytoreduction were three times as likely to die as those given HAC (RR 3.3, 95%; CI 1.2-9.3). The estimated median survival of patients treated with cryotherapy alone was 245 days, whereas for those given more than 3 months of HAC plus cytoreduction therapy it was 570 days. It is recommended that all patients who receive cryotherapy for multiple liver metastases from colorectal rectal carcinoma be given subsequent hepatic artery chemotherapy.

Cryotherapy of liver tumours--a practical guide.

The use of cryotherapy for the treatment of some unresectable liver tumours has been clearly established as a therapeutic option. Intra-operative ultrasound has enhanced the process by enabling the surgeon to identify hepatic lesions and to allow visualisation of the freezing process to ensure that the cryolesion will include the tumour mass. The purpose of this paper is to provide a practical guide to surgeons who wish to perform cryotherapy of liver tumours. Patient selection and anaesthetic considerations are important. The surgeon should be able to deal with the complications of cryotherapy, particularly the intra-operative haemorrhage which may arise from cracking of the hepatic parenchyma as the iceball thaws. Follow-up is based on tumour marker assay and imaging of the liver and repeat cryotherapy can be considered for selected cases.